Grass growing as lawns, on golf course fairways and on putting and bowling greens, collectively termed turf, grows best when the thatch layer is not excessive. Thatch is the matted, often partially decaying, plant matter at the soil line. It is made up of stolons, rhizomes and horizontally growing grass blades as well as cut and decaying grass clippings. Removal of the thatch, which allows the new shoots of grass to sprout, for most lawns need not be done very often because the build-up of the plant material making up the thatch is about equal to its decay into humus.
The situation for closely cropped, dense turf, such as putting greens and bowling greens, is different. Such dense turf, because of the use to which they are subjected, is well fertilized so it grows fast and thick and may be cut daily for proper care. In addition to the naturally horizontally growing rhizomes and stolons, some grass and other plants grow horizontally in response to frequent mowing. The net result is fast thatch buildup which reduces the turf quality.
Complete removal of the thatch causes the destruction of the turf. To keep the thatch within desirable limits, the turf must be periodically renovated. This is typically done using a conventional mower attachment called a thatcher. The thatcher is used to cut a series of grooves in the turf to dislodge some of the matted organic matter. These renovation projects are expensive due to the direct cost of renovation and since the golf course must be shut down for a few days because of the temporary damage to the turf.